The evalInSandbox implementation in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 uses an incorrect context during the handling of JavaScript code that sets the location.href property, which allows remote attackers to conduct cross-site scripting (XSS) attacks or read arbitrary files by leveraging a sandboxed add-on.